1. Field of the Invention
The present invention relates to gallium phthalocyanine compound, and an image bearing member, an image forming method, an image forming apparatus, and a process cartridge using the gallium phthalocyanine compound.
2. Description of the Background Art
Phthalocyanine compounds are widely used as electronic materials and in recent years have been widely studied for their applicability particularly in fields such as electrophotography, optical recording, and photoelectric conversion elements.
With regard to the electrophotography field, many phthalocyanine compounds having sensitivity in the near-infrared wavelength area of semi-conductor lasers have been studied and researched, in an effort to improve both the sensitivity of electrophotographic image bearing members and the stability thereof for an extended period of time with an emphasis on the crystal types of such phthalocyanine compounds.
In general, phthalocyanine compounds are known to have a variety of crystal types depending on manufacturing and processing methods. Such crystal types are also known to have significant impacts on photoelectric conversion efficiency and image bearing member stability over an extended period of time with repetitive use.
With regard to the phthalocyanine compound crystal types, for example, copper phthalocyanine has crystal types of α, π, χ, ρ, γ, δ, etc. in addition to stable β type. These crystal types are known to be mutually transitioned among them by mechanical external force, sulfuric acid treatment, organic solvent treatment, heat treatment, etc.
In addition, Japanese patent application publication nos. H05-98181 (hereinafter referred to as JP-H05-98181-A), JP-H05-263007-A, JP-HP-07-53892-A, JP-2009-62475-A, and JP-2001-323183-A describe gallium phthalocyanine compounds. However, hydroxy gallium phthalocyanine compounds described therein have generally extremely low solubility in organic solvents. Therefore, refinement is limited to washing by organic solvents. Thus, impurities are difficult to sufficiently remove.
In addition, many methods of synthesizing gallium phthalocyanine compounds using acid paste have been described but use strong sulfuric acid, which tends to cause problems in handling, limits the applicable range of pigments, and adversely impacts electrical characteristics of the image bearing member due to resolvents produced by strong sulfuric acid.
For these reasons, the present inventors recognize that a need exists for gallium phthalocyanine compounds that have a large solubility in organic solvents to improve the quality and stability of images produced by an image forming apparatus employing electrophotography (e.g., photocopier, laser printer), and an image bearing member, an image forming method, an image forming apparatus, and a process cartridge using the gallium phthalocyanine compounds.